Hatch cover assembly



Nov. 2, 1965 Filed March 1l, 1963 P. RICHTER ETAL HATCH COVER ASSEMBLY 4Sheets-Sheet 1 l l I l Nov. 2, 1965 P. RICHTER ETAL HATCH covER ASSEMBLY4 Sheets-Sheet 2 Filed March 11, 1965 S a 5 Ref Mv, mi im mi. :A Vp/A aP i A Z Z f, Y B s U fx Ill/HU @@lr Q n N .v m w wm, mw mw wm wm mm* mwN N /m o Jr o mm, A n mmv w \N mmf@ mm Q mlm WARN m \,wmm mm WN Nm.

Nov. 2, 1965 P. RICHTER ETAL HATCH COVER vASSEMBLY F'ild March 1l. 19634 Sheets-SheetI 3 ATTORNEYS' P. RICHTER ETAL 4 Sheets-Sheet 4 HATCHCOVER ASSEMBLY Nov. 2, 1965 Filed March l1,- 1963 M, MM n M UnitedStates Patent O 3,215,191 HATCH COVER ASSEMBLY Philip Richter,Bethlehem, and Meade H. Detweiler,

Catasauqua, Pa., assignors to Fuller Company, a corporation of DelawareFiled Mar. 11, 1963, Ser. No. 264,307 2 Claims. (Cl. 1150-206) Thisinvenion relates to the art of hatch covers, and more particularly to ahatch cover which, when closed will be substantially llush with thelevel of the deck through which the hatchway extends.

As conducive to an understanding of the invention it is noted that wheremarine hatch covers comprise a plurality of substantially rectangularpanels which are mounted on a coamingextending above the deck levelaround the periphery of the hatchway, such arrangement would interferewith free movement of personnel as well as that of tractors or forklifts required to shift cargo, which is especially undesirable where thehatch cover is on a deck below the top or weather deck of a ship notreadily accessible to the ships boom for movement of cargo.

Where the hatch cover when in closed, substantially horizontal positionis ush with the deck and there are spaces or gaps of excessive widthbetween the periphery of the hatchway and the periphery of the hatchcover, the spaces or gaps may cause tripping of the crew members orjamming of the wheels of tractors or fork lifts required to move cargo.

Where the hatchway is closed by means of a cover assembly of the flushdeck type, comprising at least three substantially rectangular panelswhich are hinged together and which extend across the hatchway with oneend of the assembly being pivotally mounted at one end of the hatchwayon a support fixed thereto and with the pair of panels adjacent thepivotal support folding together about a common hinge and the additionalpanel adjacent said pair folding on a common hinge toward said pair ofpanels, if upon initial folding movement of the pair of panels fromtheir original horizontal closed position, the additional panel shouldmove away from the pivotal mount of the assembly, unless suicient clearance is afforded between such additional panel and the adjacent edge ofthe deck opening, they would abut with resultant deformation thereof andpossible misalignment of said panels with resultant jamming thereof `andif suliicient clearance is provided, it may result in a gap of excessivewidth with the difficulties above pointed out.

It is accordingly among the objects of the invention to provide a hatchcover installation having at least three pivotally connected panels,that is relatively simple to install and which, when in closed positionwill have the top surface of the panels in substantially horizontalposition substantially flush with the deck of the ship and with noexcessive clearance between the periphery of the cover and the peripheryof the hatchway in the deck which might cause tripping of crew membersor jamming of the wheels of a tractor or fork lift, which hatch covermay readily and rapidly be moved from closed to open position and viceversa without undue effort on the part of the crew by folding two of thepanels toward each other and the additional panel toward the otherpanels and without jamming of the hatch cover panels against the edge ofthe `deck opening.

According to the invention these objects are accomplished by thearrangement and combination of elements hereinafter described and moreparticularly recited in the claims.

In the accompanying drawings in which are shown one or more of variouspossible embodiments of the several features of the invention,

3,215,191 Patented Nov. 2, 1965 FIG. 1 is a plan View of a hatch coverinstallation of the type having four panels according to one embodimentof the invention;

FIG. 2 is a longitudinal sectional view taken along line 2-2 of FIG. 1;

FIGS. 3 to 5 inclusive are diagrammatic views illustrating the operationof the equipment;

FIGS. 6 to 8 inclusive are views showing the panels in various openingpositions;

FIG. 9 is a side elevational view showing the panels in completely openposition;

FIG. 10 is a top elevatorial view showing the link connector, accordingto the invention;

FIG. 11 is a View taken along line 11-11 of FIG. 10;

FIG. 12 is a detail sectional view taken along line 12-12 of FIG. l;

FIG. 13 is a view similar to FIG. 12 taken along line 1313 of FIG. 1;

FIG. 14 is a detail view taken along line 14-14 of FIG. l showing thedepression in the track, and

FIG. 15 is a diagrammatic view showing another embodiment of theinvention.

Referring now to the drawings, in the illustrative embodiment shown, thedeck 21 of the ship has a substantially rectangular opening thereindefining a hatchway 22, which, as shown in FIGS. 2, l2 and 13, forexample, has a ledge 23 extending the length of the hatchway on eachside thereof and spaced below the level of the deck. Each of the ledges23 supports an elongated substantially rectangular track or support bar24 clearly shown in FIGS. 2, l2 and 13. One of the ends of the hatchwayhas a support beam 25 extending transversely thereacross, illustrativelyin the same plane as the tracks 24. The ledges 23 and 25 serve tosupport a hatch cover assembly 26 in the manner hereinafter to bedescribed.

The hatch cover assembly illustratively comprises two pairs ofsubstantially rectangular panels A, B and C, D. The panels are ofsuicient length so that they may extend transversely across thehatchway, the length of said panels being slightly less than the widthof the deck opening 22 which defines the hatchway. The panels are ofsuch width that when in closed position they will extend fromsubstantially one end of the deck opening 22 to the other as is clearlyshown in FIG. 1 substantially to close the hatchway.

Referring to FIG. 2, it is to be noted that each of the panels has adepending skirt plate 28 located slightly inward from the outerperiphery of each panel. The lower edge of each skirt is illustrativelyprovided with a reinforcing strip 29 extending the length thereof whichis designed to seat on the associated track or support bar 24 as isclearly shown in FIGS. 2 and 12, for example, thereby supporting thepanels in a horizontal plane when in closed position on said supportbars 24.

As is clearly shown in the drawings, the skirt plate 28 along the outerside of panel A mounts a plurality of arms 31, illustratively two innumber which extend outwardly from said skirt plate 28. The free end ofeach of the arms 31 is pivotally connected as at 32 to the top of anassociated upright standard 33, aixed to the ledge 25, the height ofsuch standard 33 being such that the pivot connection 32 illustrativelywill be below the level of the deck 21 as is clearly shown in FIG. 2 andthe thickness of each of the panels being such that its top surface 33when the panels are in closed position, will be substantially ush withthe deck 21.

The adjacent inner edges 35, 35 of the panels A, B and C, D at theirlower edges are connected as by means of common hinges 36 (FIG. 2), thehinges being secured to the adjacent skirt plates 28 of said panels, sothat the pairs of panels A, B and C, D may be folded about such hinges36 respectively from the closed position shown in FIG. 2 to the openposition shown in FIG. 9 in the manner hereinafter to be described.

According to the invention the adjacent panels B and C are connected bymeans of pivoted links 4l, two of which are illustratively provided asis shown in FIG. 1.

To support the links the adjacent skirt plates 28 of panels B and C havesecured thereto as shown in FIGS. 1 and 2 and l0, two pairs of spacedparallel mounting plates 44, said plates depending from the top surface33 of said panels and being secured as by welding at their edges to thetop surface and to the skirt plate 28. Desirably, a reinforcing bar 45which extends the length of each of the panels B and C is provided towhich the lower edges of the support plates 44 are secured as bywelding.

As is clearly shown in FIGS. l, 2 and 10, the associated portions of thetop surface of the panels B and C near their adjacent edges 46, 46' haveslots Sti therein to accommodate the links 41. Each of the links 41 ispositioned between associated pairs of support plates 44 of the panels Band C as is clearly shown in FIG. and is pivotally connected between theplates 44 as by pivot pins 47, 48 which extend through appropriateopenings 49, 51 in the link 41. Desirably, each of the openings 49, 51is provided with a bushing 52, 53 respectively.

The opening 49, as is clearly shown in FIG. 1l, for example, is definedby an elongated slot and the opening 51 is circular. Thus, the pin 47and the link 41 are capable of relative movement with respect to eachother. Also associated with the panel B and extending transverselybetween the side plates 44 is a stop pin 55, clearly shown in FIG. 1l,the purpose of said pin being hereinafter described.

To facilitate movement of the panels A, B and C, D from closed to openposition and vice versa, in the manner hereinafter to be described, thepanel B at each end 56 adjacent its outer edge 46 mounts a flangedroller 57, rotatably mounted on a shaft 58 extending laterally outwardlyfrom the side plate 59 (FIG. 1) and the panel C at each end 62 mounts aflanged roller 63 rotatably mounted on a shaft 64 extending laterallyoutwardly from a depending plate 65 as is clearly shown in FIGS. 1 and13. As is clearly shown in FIGS. 1 and 13, the flanged rollers 57 and 63are mounted on the outside of plate 59 and the inside of plate 65respectively and ride 'on the track 24. Similarly, a anged roller 57 isprovided on the end 66 of panel D adjacent the outer edge 67 thereof,the rollers 57 being rotatably mounted on the outer side of dependingplate 65 and longitudinally aligned with the rollers 57.

In the closed position of the hatch cover panels as is shown in FIGS. 1,2, 12 and 13, for example, the rollers 63, and 57' will be positioned indepressions 68 and 69 respectively. The depressions 68 and 69 are ofsuch length and depth that when the rollers 63 and 57 are alignedtherewith, the lower portion of the rollers will be spaced from thebottom as well as the sides of said depressions as is clearly shown inFIG. 14. In rthis position the weight of the hatch cover will besupported on the rails 24 by means of the reinforcing strips 29 securedto the lower edges of the skirt panels 28 of the panels C and D as isclearly shown in FIG. 2, for example. With this construction there willbe no severe load on the shafts 58, 64 which support the rollers 63, 57so that heavy cargo may be placed on the hatch cover panels when theyare in closed position. As far as the panels A and B are concerned, whenthey are in closed horizontal position, although the roller 57 of panelB will rest on the associated rail 24 as is clearly shown in FIG. 13,when in closed position the bars 29 will rest on the rails 24 to takethe load off the shafts of the rollers 57.

Although the panels A, B and C, D may be moved in any suitable mannerfrom the closed position shown in FIG. 1 in which they lie in side byside relationship in a horizontal plane, to the open position shown inFIG. 9 in which they extend parallel to each other in a vertical 4plane, in the embodiment shown in FIGS. 1 to 14, hydraulic means arepreferably employed which may be of the type shown in reissue No. 24,238dated November 13, 1956.

To this end, referring to FIG. 2, a reaction member, preferably a plate71, is provided which may be substantially triangular in shape and hasan opening 72, 73, 74 at each of its corners and is desirably positionedin a vertical plane with a pin 75 which defines the axis of hinge 36extending freely through the bottom opening 74.

Reacting against each of the plates 71 is a pair of opposed hydraulicunits 77, 78 mounted respectively in panels A, B and C, D. The rear endsof each of the units 77, 78 is preferably piv-otally mounted as at 79 toan associated beam 81. The outer ends of the reciprocable plungers 82,83 of the units 77, 78 respectively are pivotally connected to `anassociated reaction plate 7l by means of pins extending through theouter ends of the plunger and the openings 72, 73 respectively. Thehydraulic units 77, 78 are illustratively of the double acting type andeach has a control port 86, 87 at its respective end on each side of thepiston (not shown) slidably mounted thereon.

It is to be noted as diagrammatically shown in FIG. 3, for example, andalso in FIG. 2, that when the panels are in closed horizontal positionover the hatchway, lines drawn between pivot 32, hinge 36 and axle ofthe roller 57 will form a triangle having its base line uppermost andits vertex, which illustratively defines an obtuse angle pointeddownwardly. In addition, the hinge 36 will be below the base line of thetriangle above described.

To open the hatchway, suitable valves controlling a source of fluidunder pressure may be actuated so that such tluid under pressure willbeapplied to the ports 87 of the hydraulic units 77, 78 of panels A, Bin the first instance in direction to move the pistons thereof towardeach other. As a result, an upward component of force will be exertedagainst the hinge pin 7 S and the two panels A, B will move upwardlyfrom their normal horizontal position.

As the panel A is pivotally mounted as at 32 in fixed position withrespect to the deck of the ship, the initial upward movement of thepanels will cause the hinge 36 to rise in an arcuate path as shown inFIG. 3 and at first such hinge will move to the right away from thepivot connection 32, and such movement will cause the panel B to moveslightly lto the right. Without the presence of the pivoted link 41,this movement would be transmitted to the panels C and D causing them tomove to the right also and consequently, the edge 67 of the panel Dwould jam against the adjacent edge 88 of the hatch opening in the deck,causing injury or damage to both the edge of the deck and the adjacentedge 67 of the panel D. In addition, due to the restriction of movementof panel D, the pair of panels C, D would tend to fold and this couldcause the rollers thereof to be dislodged from the tracks 24. Theseproblems are eliminated by the presence of the slotted links 41.

Thus, referring to FIGS. 3, 4 and 11, for example, as the panel A startsits initial folding movement and the panel B is moved slightly to theright, by reason of the slot 49 in link 41, the pin 47 will be free tomove to the right without imparting any movement to the panels C and D.The spacing between the adjacent edges 46, 46' of panels B and C issufficient to permit the necessary movement of the panel B withoutcausing abutment of the edges 46, 46 and of course the slot 49 is oflength sufiicient to accommodate such movement. When the panels: A and Bhave been pivoted upwardly a slight amount, the: hinge 36 will rise inan .arcuate path away from the pivot: connection 32 until it is alignedwith the base line of the triangle as shown in FIG. 4. From this pointon with continued folding movement of the panels A. and B, the hinge 36will continue its arcuate path, but now '[.QWJJdl the hinge point 32 asshown in FIG. 5.

As the panels A and B are folded from the position shown in FIGS. 3 and6 to the position shown in FIGS. 5 and 8, for example, the stop pin 55which is iixed with respect to the panel B, will also move in an arcuatepath from its position beneath the link 41 as shown in FIG. 3 to aposition where it is immediately in front (to the left) of the link andabutting there against as shown in FIG. 5. Similarly, at the positionshown in FIGS. 4 and 7, the panel B will have reached its maximumposition of movement to the right so that the pivot pin 47 will be atthe right end of the slot 49 in the link 41 and when it has reached theposition shown in FIGS. 5 and 8, i.e., when the panel B has gone pastthe position shown in FIGS. 4 and 7, the pin 47 will be at the left endof the slot 49.

At this time with further folding movement of the panel-s A and YB, theforce exerted by the pins 47 on the ends of link 41 will move panels Cand D, which are still in horizontal position, to the left. This willcause the rollers `63, 57 of panels C and D to ride out of theassociated depressions 68, 69.

When the rollers of panels C and D reach the top of the sloped side ofthe depressions, the force required to move the panels C and D willimmediately be greatly reduced. Due ot the force exerted on panels C andD through the link connection to panel B, the panels C and D would tendto move to the left taking up the lost motion in the slot and jar andpossibly damage the panels.

However, by reason of the fact that when the rollers of panels C and Drise out of Athe depressions 68, 69 and are free, the stop pin 55 willbe, at this time, in front of and against the associated link 41 so thatthe link will be -restrained from movement, consequently, even thoughthe force required to move the panels C and D is reduced, there will beno sudden movement of such panels to the left.

With continued -force applied to the panels A and B through actuators77, 78, the panels A and B will reach their booked or completely foldedposition. When panels A and B reach their booked position, panels C andD are still in the horizontal position, and due to momentum, panels Cand D tend to continue moving toward panels A and B. Without stop pin 55being present, when panels A and B were stopped, panels C and D couldcontinue movement until all of the slack in slot 49, of link 41 weretaken up. In this position, were panels C and D being booked, the edge46 of panel C would gouge into and damage the upper surface of panel Bas well as interfere with the booking of panels C and D. However, stoppin 55 prevents the slack in slot 49 from being taken up since pin 55engages link 41 and limits the movement of panels C and D to keep thenecessary spacing between panels B and C so that there will be clearancebetween these panels to allow booking of panels C and D withoutinterference and without damage to any of the panels. At the time panelsA and B reach their booked or completely folded position, valves areactuated so that the hydraulic actuation of panels C and D will beenergized. Thus, the panels C and D will start to yfold to closedposition until all four panels are fully folded at the left end of thehatchway as is shown in IFIG. 9.

It is to be noted that the rollers 57, 63 as well as the rollers 57 areof such dimensions that their edges extend slightly beyond the edges ofthe associated panel to permit the requisite folding action so that thelower edges of the skirt plates will be moved clear of the rails onwhich they ride.

If desired, the panels may be moved to open position by means of thereeving arrangement shown in FIG. and the hydraulic actuators may beeliminated. To this end, a cable 91 is provided which is operativelydriven by the Winch of a ship. The cable 91 extends around a pulley 92and then around a pulley 93 connected to a lift pad 94 pivotally mountedon panel A. The cable 91 after passing around pulley 93 is then passedaround a pulley 95 located adjacent pulley 92 and connected at its freeend to a lift tab 96 pivotally connected to panel C. When the winch isenergized, since the force acting on panel A is twice that acting onpanel C, the panels A and B will first be folded before panels C and Dare folded.

Pin 51 is also important in the FIG. l5 arrangement. In thisarrangement, since a continuous external force is exerted on panel Cthrough tab 96 tending to move panels C and D toward panels A and Bimmediately upon removal of the rollers from their recesses panels C andD would move quickly toward panels A and B, taking up the lost motion inthe slot, and knock into panel B with great force with possiblederailment of the rollers, were pin 51 not present. In addition, pin 51is effective in preventing interference with the booking of panels C andD and damage to the panels after panels A and B are stopped in thecompletely booked position.

With the constructions above described, there is no need to have thepivotal connection 32 of the panel A at a suiiicient depth below thelevel of the deck so that with initial folding movement, the hingeconnection 36 will immediately move to the left rather than to theright. Such arrangement is undesirable as it would require that thethickness of the panels be increased thereby requiring not only arelatively deep opening to accommodate the pivotal connection 32, butthe space between the edge of the panel A and the connection 32 wouldalso have to be increased resulting in a gap of excessive width in thedeck.

In addition, with such a thicker panel, when the panels are pivoted tovertical position since there would be considerable Weight on each sideof the pivotal connection 32, the vertical panels could tilt forwardlyover the hinge connection thereby disabling the hatch cover assembly.

With the slotted hinge arrangement herein described the hinge connectioncan be located adjacent the deck level thereby avoiding the problemsabove noted.

As many changes could be made in the above construction, and manyapparently widely different embodiments of this invention could be madewithout departing from the scope of the claims, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

1. A cover assembly for a hatchway in the deck of a ship, comprising apair of panels, adapted to extend over said hatchway, said panels lyingin side by side relation in substantially a horizontal plane when inclosed position, means pivotally mounting an edge of one of said panels,said pivotal mount being located at one end of the hatchway, meanspivotally connecting the adjacent edges of said panels for foldingmovement thereof between closed and open position, a roller mounted onsaid other panel at each end of the opposite edge of the other panel, atrack positioned on each side of the hatchway on which said rollers rideto guide the opposite edge of the other of said panels in substantiallya horizontal plane, additional panel means adapted to lie in side byside relation with said pair of panels when in closed position over thehatchway, all of said panels when in closed position having their outerperipheries adjacent the periphery of the hatch opening in the deck,means pivotally connecting said additional panel means to the adjacentpanel of said pair, said connecting means comprising a link having anelongated opening at one end and a substantially circular opening at theother, a pair of pivot pins fixed with respect to and carriedrespectively by said additional panel means and said adjacent panel, andextending respectively through said circular opening and said elongatedopening, said elongated opening defining a lost motion slot to permit apredetermined movement of said pair of panels independently of said.additional panel means, said pivotal connection between adjacent edgesof said pair of panels lying below a plane extending between saidpivotal mount and the centers of said rollers when said panels are inclosed position, and a rigid stop member carried by said adjacent paneland extending outwardly thereof beneath and in juxtaposition to saidlink when said panels are in horizontal position, said stop member beingclear of said link when the pair of panels are in substantiallyhorizontal position and being moved in alignment with said link andadjacent the end thereof having an elongated opening for abutment ofsuch end thereagainst to restrain relative movement between the link andthe pin extending through such elongated opening after said pair ofpanels have folded toward each other by an amount such that the pivotalconnection between the adjacent edges of said pair of panels lies abovea plane extending between said pivotal mount and the centers of saidrollers.

2. The combination set forth in claim 1 in which said additional panelmeans comprises a second pair of panels, means pivotally connectingadjacent edges of said second pair of panels, a roller at each end ofthe edge of the panel of said second pair pivotally connected to theiirst pair of panels, and a -roller at each end of the edge of the otherpanel of said second pair adjacent the other end of the hatchway, saidrollers of said second pair of panels riding on said tracks, each ofsaid tracks having a depression in which said rollers of said secondpair of panels are positioned when said two pairs of panels are inclosed horizontal position over said hatchway, and means to support saidpanels with the peripheries of said rollers of said second pair spacedfrom the Walls of said depressions when said two pairs of panels are inclosed horizontal position.

References Cited by the Examiner UNITED STATES PATENTS 2,484,286 10/49Groppell 160l88 X 2,770,297 ll/ 56 Mercier et al. 160-188 2,943,675 7/60Ford 1GO-4206 3,043,257 7/ 62 Appleton et al 114-202 3,114,346 12/63Dahlin 160-188 XR FOREIGN PATENTS 168,626 9/59 Sweden.

HARRISON R. MOSELEY, Primary Examz'ner.

1. A COVER ASSEMBLY FOR A HATCHWAY IN THE DECK OF A SHIP, COMPRISING APAIR OF PANELS, ADAPTED TO EXTEND OVER SAID HATCHWAY, SAID PANELS LYINGIN SIDE BY SIDE RELATION IN SUBSTANTIALLY A HORIZONTAL PLANE WHEN INCLOSED POSITION, MEANS PIVOTALLY MOUNTING AN EDGE OF ONE OF SAI PANELS,SAID PIVOTAL MOUNT BEING LOCATED AT ONE END OF THE HATCHWAY, MEANSPIVOTALLY CONNECTING THE ADJACENT EDGES OF SAID PANELS FOR FOLDINGMOVEMENT THEREOF BETWEEN CLOSED AND OPEN POSITION, A ROLLER MOUNTED ONSAID OTHER PANEL AT EACH END OF THE OPPOSITE EDGE OF THE OTHER PANEL, ATRACK POSITIONED ON EACH SIDE OF THE HATCHWAY ON WHICH SAID ROLLERS RIDETO GUIDE THE OPPOSITE EDGE OF THE OTHER OF SAID PANELS IN SUBSTANTIALLYA HORIZONTAL PLANE, ADDITIONAL PANEL MEANS ADAPTED TO LIE IN SIDE BYSIDE RELATION WITH SAID PAIR OF PANELS WHEN IN CLOSED POSITION OVER THEHATCHWAY, ALL OF SAID PANELS WHEN IN CLOSED POSITION HAVING THEIR OUTERPERIPHERIES ADJACENT THE PERIPHERY OF THE HATCH OPENING IN THE DECK,MEANS PIVOTALLY CONNECTING SAID ADDITIONAL PANEL MEANS TO THE ADJACENTPANEL OF SAID PAIR, SAID CONNECTING MEANS COMPRISING A LINK HAVING ANELONGATED OPENING AT ONE END AND A SUBSTANTIALLY CIRCULAR OPENING AT THEOTHER, A PAIR OF PIVOT PINS FIXED WITH RESPECT TO AND CARRIEDRESPECTIVELY BY SAID ADDITIONAL PANEL MEANS AND SAID ADJACENT PANEL, ANDEXTENDING RESPECTIVELY THROUGH SAID CIRCULAR OPENING AND SAID ELONGATEDOPENING, SID ELONGATED OPENING DEFINING A LOST MOTION SLOT TO PERMIT APREDETERMINED MOVEMENT OF SAID PAIR OF PANELS INDEPENDENTLY OF SAIDADDITIONAL PANEL MEANS, SAID PIVOTAL CONNECTION BETWEEN ADJACENT EDGESOF SAID PAIR OF PANELS LYING BELOW A PLANE EXTENDING BETWEEN SAIDPIVOTAL MOUNT AND THE CENTERS OF SAID ROLLERS WHEN SAID PANELS ARE INCLOSED POSITION, AND A RIGID STOP MEMBER CARRIED BY SAID ADJACENT PANELAND EXTENDING OUTWARDLY THEREOF BENEATH AND IN JUXTAPOSITION TO SAIDLINK WHEN SAID PANELS ARE IN HORIZONTAL POSITION, SAID STOP MEMBER BEINGCLEAR OF SAID LINK WHEN THE PAIR OF PANELS ARE IN SUBSTANTIALLYHORIZONTAL POSITION AND BEING MOVED IN ALIGNMENT WITH SAID LINK ANDADJACENT THE END THEREOF HAVING AN ELONGATED OPENING FOR ABUTMENT OFSUCH END THEREAGAINST TO RESTRAIN RELATIVE MOVEMENT BETWEEN THE LINK ANDTHE PIN EXTENDING THROUGH SUCH ELONGATED OPENING AFTER SAID PAIR OFPANELS HAVE FOLDED TOWARD EACH OTHER BY AN AMOUNT SUCH THAT THE PIVOTALCONNECTION BETWEEN THE ADJACENT EDGES OF SAID PAIR OF PANELS LIES ABOVEA PLANE EXTENDING BETWEEN SAID PIVOTAL MOUNT AND THE CENTERS OF SAIDROLLERS.